Stator for motor and motor

Abstract

An electric machine operable as a motor or generator includes a stator having a body portion substantially in the shape of a hollow column with an outer wall and an inner wall. The body portion has a plurality of first slots and a plurality of second slots each running through the body portion in a longitudinal direction. The plurality of first slots are distributed in a circumferential direction between the outer wall and the inner wall, and the first slots are circumferentially closed slots. The plurality of second slots are distributed in the circumferential direction between the first slots and the inner wall, and the second slots are circumferentially closed slots and are spaced apart from the first slots.

What is claimed is: 
     
       1. A stator for a motor, comprising:
 a hollow column shaped body portion having an outer wall and an inner wall and defining a plurality of first slots running through the body portion in a longitudinal direction and distributed in a circumferential direction between the outer wall and the inner wall, the plurality of first slots being circumferentially closed slots, the body portion also defining a plurality of second slots running through the body portion in the longitudinal direction and distributed in the circumferential direction between the plurality of first slots and the inner wall, the plurality of second slots being circumferentially closed slots and being spaced apart from the plurality of first slots, wherein length of each of the plurality of first slots is in a range between 10 mm to 20 mm, and width of each first slot is in a range of 2 mm to 5 mm; and wherein length of each second slot is in a range of between 0.1 mm to 0.3 mm, and width of each second slot is in a range of between 1 mm to 2 mm. 
 
     
     
       2. The stator according to  claim 1 , wherein each of the plurality of second slots has a rectangular cross section extending in the circumferential direction of the stator, a width of the rectangular cross section in the circumferential direction being greater than length thereof in a radial direction, and length of each second slot being less than length of each of the plurality of first slots in the radial direction. 
     
     
       3. The stator according to  claim 1 , wherein each second slot has one of a rectangular cross section, a circular cross section, a trapezoidal cross section, or a cross section formed by a combination thereof. 
     
     
       4. The stator according to  claim 1 , wherein a ratio of length of each second slot in a radial direction to a radial distance between each first slot and the inner wall is at least 15%. 
     
     
       5. The stator according to  claim 1 , wherein each of the plurality of first slots corresponds to one unique second slot, and a radius passing through a center of the corresponding unique second slot coincides with a radius passing through a center of the corresponding first slot. 
     
     
       6. The stator according to  claim 5 , wherein a ratio of a width of the second slot in the circumferential direction to a width of the corresponding first slot in the circumferential direction is in a range of between 30% and 60%. 
     
     
       7. A stator for a motor, comprising:
 a hollow column shaped body portion having an outer wall and an inner wall and defining a plurality of first slots running through the body portion in a longitudinal direction and distributed in a circumferential direction between the outer wall and the inner wall, the plurality of first slots being circumferentially closed slots, the body portion also defining a plurality of second slots running through the body portion in the longitudinal direction and distributed in the circumferential direction between the plurality of first slots and the inner wall, the plurality of second slots being circumferentially closed slots and being spaced apart from the plurality of the first slots; 
 wherein each first slot corresponds to two unique second slots, and the corresponding unique two second slots are symmetrically arranged on two sides relative to a radius passing through a center of the corresponding first slot; and 
 wherein a ratio of a sum of the widths of the corresponding two unique second slots in the circumferential direction and the distance between the corresponding two unique second slots to the width of the corresponding first slot in the circumferential direction is in a range pf between 30% and 60%. 
 
     
     
       8. A stator for a motor, comprising:
 a plurality of annular laminates stacked in a longitudinal direction, each laminate having an inner edge and an outer edge and comprising: 
 a plurality of first holes distributed in a circumferential direction between the inner edge and the outer edge, the first holes being circumferentially closed holes; and a plurality of second holes distributed in the circumferential direction between the inner edge and the first holes, the second holes being circumferentially closed holes and being spaced apart from the first holes and the inner edge, wherein length of each first hole in a radial direction is in a range of 10 mm to 20 mm, and width of each first hole in a circumferential direction is in a range of 2 mm to 5 mm; and length of each second hole in a radial direction is in a range of 0.1 mm to 0.3 mm, and a width of each second hole in a circumferential direction is in a range of 1 mm to 2 mm. 
 
     
     
       9. The stator according to  claim 8 , wherein a ratio of length of each second hole in a radial direction to radial distance between each first hole and the inner edge is at least 15%. 
     
     
       10. The stator according to  claim 8 , wherein the second hole is rectangular, circular, trapezoidal, or a combination thereof. 
     
     
       11. The stator according to  claim 8 , wherein each first hole corresponds to a unique plurality of second holes symmetrically distributed relative to a radial centerline of the corresponding first hole. 
     
     
       12. The stator according to  claim 8 , wherein one first hole corresponds to only one second hole, and a radial centerline of each second hole coincides with the radial centerline of the corresponding first hole. 
     
     
       13. The stator according to  claim 8 , wherein the outer edges and inner edges of the plurality of laminates respectively form an outer wall and an inner wall of the stator, and the inner wall defines a cavity for accommodating a rotor; and the first holes of the plurality of laminates are superposed in the longitudinal direction to form a plurality of first slots for accommodating windings of the motor, and the second holes of the plurality of laminates are superposed in the longitudinal direction to form a plurality of second slots.